Phosphorus containing flame retarding agents which are reactive with isocyanates

ABSTRACT

This invention relates to novel flame retarding agents and processes in which they are used in the production of polyurethanes. These compounds are represented by the general formula: ##STR1## wherein: A and B, which are identical or different, represent optionally branched C 1  -C 17  -alkyl groups or --OR groups wherein R represents an optionally branched C 1  -C 8  -alkyl group, and 
     X represents hydrogen, halogen, an optionally branched C 1  -C 8  alkyl group, a C 6  -C 12  aryl or aralkyl group, NH 2 , CF 3 , CN, COOR&#39;, SO 3  R&#39;, ##STR2## wherein: R&#39; represents hydrogen or an optionally branched alkyl or cycloalkyl group having 1-10 C atoms and 
     R&#34; represents an optionally branched alkyl or cycloalkyl group having 1-10 C atoms.

BACKGROUND OF THE INVENTION

It is known that the flame resistance of synthetic resins and inparticular polyurethane resins can be increased by adding unreactive lowmolecular weight phosphoric or phosphonic acid esters to them duringtheir preparation. This procedure is, however, limited by the fact thatif the desired mechanical properties are to be obtained, only limitedquantities of low molecular weight compounds may be added, suchquantities being insufficient for complete flame protection. Theprocedure is also limited by the fact that the additives tend to migratefrom the resin due to their low molecular weight.

Attempts have been made to overcome this difficulty by incorporatinghalogen-containing polycarboxylic acids or polyhydroxyl compounds intothe molecular structure. Halogenated components of this kind include,for example, tetrachlorophthalic acid, dibromophthalic acid andhexachloroendomethylene tetrahydrophthalic acid. Although the flameresistance of polyesters prepared from such components is substantiallyimproved, for example, after they have been foamed with polyisocyanates,it is still insufficient in many cases. Other disadvantages lie in thefact that these polyesters are difficult to mix with polyisocyanates atroom temperature because of their high viscosity. Processingdifficulties then occur during the production of foams. Moreover, thesepolyesters frequently give rise to brittle foams so that they can onlybe converted into foams having good mechanical properties if they arefirst blended with the conventional polyesters. However, in that case,the flame resistance is partly lost. Moreover, many of the conventionalhalogen containing flame retarding agents liberate corrosive gases suchas hydrogen chloride or hydrogen bromide on combustion.

Flame resistant polyurethane resins having good mechanical propertiescan be obtained when using polyisocyanates which contain phosphoric acidor thiophosphoric acid groups, e.g. phosphoric acid(p-isocyanatophenyl)-triesters. The phosphoric ester triisocyanates usedcan, however, only be obtained by multistage processes and their use istherefore often uneconomical.

Hydrocarbon phosphonyl diisocyanates have also been used for theproduction of flame resistant foams. These diisocyanates, however, areacylisocyanates which are not only physiologically undesirable becauseof their odor and vapor pressure but which are also particularlyundesirable because of their excessive reactivity and the ease withwhich they can be saponified. Thus, usable foams can be obtained fromthem only if they are mixed with considerable proportions ofconventional polyisocyanates such as tolylene diisocyanate. It isobvious, of course, that in that case, they lose their flame retardingproperties.

It is also known in the art that phosphorus containing polyethers andpolyesters can be used for the production of polyurethane foams. Theseproducts, however, produce fumes in considerable quantities when exposedto heat. Moreover, in many cases they are difficult to process becauseof their viscosity which can give rise to difficulties in foaming.

DESCRIPTION OF THE INVENTION

It has now been found that non-flammable or substantially non-flammablepolyurethane resins can be obtained without the disadvantages generallyinvolved with using the known flame retarding agents mentioned above byutilizing novel aromatic dialkylphosphonic acid esters which are aminosubstituted on the nucleus as reactants for the preparation of thepolyurethane.

This invention therefore relates to flame retarding agents of thefollowing formula which are reactive with isocyanates: ##STR3## wherein:A and B which may be identical or different, represent optionallybranched C₁ -C₁₇ (preferably C₁ -C₈ alkyl groups) or OR groups, Rrepresenting an optionally branched alkyl group and preferably Rrepresenting an optionally branched C₁ -C₈ alkyl group and

X represents hydrogen, halogen (preferably Cl or Br), an optionallybranched C₁ -C₈ -alkyl group, a C₆ -C₁₂ aryl or aralkyl group, NH₂, CF₃,CN, COOR', SO₃ R', ##STR4## wherein: R' represents hydrogen or anoptionally branched alkyl or cycloalkyl group having 1-10 C atoms, and

R" represents an optionally branched alkyl or cycloalkyl group with 1-10C atoms.

The polyamines which are particularly preferred according to theinvention are those of the above general formula in which:

R represents a branched or straight chain C₁ -C₄ alkyl group; and

X represents hydrogen, chlorine, CH₃, NH₂ or COOR';

R' represents a branched or straight chain C₁ -C₄ -alkyl group.

The following are typical examples of the compounds according to theinvention: ##STR5##

These compounds are prepared by catalytic reduction of the correspondingpolynitro precursors in the pressure of Raney nickel at pressures of 30to 100 excess atmospheres, preferably 50 to 80 excess atmospheres andtemperatures of 20° to 120° C, preferably 35° to 60° C, using as asolvent, the alcohol which corresponds to the radical R in thephosphinic or phosphonic acid ester.

According to an earlier proposal by the present applicants (GermanOffenlegungsschrift No. 24 21 070, corresponding to British patentapplication No. 17723/75), the polynitro compounds corresponding to thepolyamines according to the invention can be obtained in high yields andpractically free from by-products by a modified Michaelis-Arbusovreaction between aromatic halogen compounds which contain nitro groupsand phosphorous acid alkyl esters or phosphonus or phosphinous acidalkyl esters.

Phosphorous acid esters suitable for the reaction are those of thegeneral formula: ##STR6## wherein R₁, R₂ and R₃ which may be identicalor different represent optionally branched C₁ -C₈ alkyl groups. It ispreferred, however, to use the trimethyl and triethyl esters because inthat case the alkyl halides produced in the reaction have a low vaporpressure and can therefore be continuously removed from the reactionmixture.

The solvents which are optionally used may be halogenated hydrocarbons,particularly toluene or xylene; or ethers, preferably dioxane; ornitriles, preferably acetonitrile; as well as other solvents which donot react with the activated aromatically bound halogen or with thephosphorous acid alkyl esters, for example dimethylformamide ordimethylsulphoxide.

Catalysts may be added to accelerate the reaction. The catalysts whichmay be used include e.g. tertiary amines such as triethylamine,tributylamine, N-methylmorpholine, N-ethyl-morpholine, N-cocomorpholine,N,N,N',N'-tetramethylethylenediamine, 1,4-diaza-bicyclo-(2,2,2)-octane,N-methyl-N'-dimethylaminoethylpiperazine, N,N-dimethylbenzylamine,bis-(N,N-diethylaminoethyl)adipate, N,N-diethylbenzylamine,pentamethyldiethylenetriamine, N,N-dimethylcyclohexylamine,N,N,N',N'-tetramethyl-1,3-butanediamine,N,N-dimethyl-β-phenylethylamine, 1,2-dimethylimidazole and2-methylimidazole.

Acid amides such as dimethylformamide, dimethylacetamide, anddiethylformamide or urea derivatives such as tetramethylurea are alsosuitable catalysts. The addition of these catalysts to the reactionmixture is particularly advisable when aromatic halogen compounds whichare comparatively inert towards nucleophilic substitution are used.

The nitrosubstituted aromatic phosphoric acid alkyl esters are generallyprepared as follows: The aromatic halogen compound is introduced intothe reaction vessel, if desired as a mixture with an inert solventand/or catalyst. The trialkylphosphite is then added in small portionswhile maintaining the reaction mixture at a temperature of 0° to 150° C,preferably 50° to 120° C. The total quantity of phosphite added is about0.9 to 3 mol, preferably 1 to 2 mol and most preferably 1 to 1.5 mol permol of halogen compound. When the calculated quantity of alkyl halidehas been formed (which can be checked, for example, by means of a gasmeter), the reaction is stopped (if necessary with cooling) and anyexcess trialkylphosphite and solvent may be removed under vacuum oralternatively the reaction mixture may be extracted with petroleum etherafter removal of the solvent.

If catalysts are used or if the aromatic halogen compounds are highlyactivated, the reactants may be mixed together in one step. In thisvariation of the process, however, it is necessary to ensure that thetemperature of the reaction mixture is kept below 70° C and preferablybelow about 60° C in in order to avoid side reactions, (e.g. thereduction of nitro groups). In this case, the reaction is stopped whenthe calculated quantity of alkyl halide has been formed. Onedisadvantage of this method is the increased reaction time, but on theother hand the quantity of undesirable by-products is generally lessthan that formed when elevated temperatures are employed withportionwise addition of the trialkylphosphite.

Phosphonous and phosphinous acid alkyl esters may also be used in ananalogous manner. One advantage of these compounds is their higherreactivity compared with that of aromatically bound halogen. Accordingto the invention, however, it is preferred to use phosphorous acidesters because they are generally more readily available.

The polyamines according to the invention are used as reactivecomponents together with polyisocyanates, high molecular weight and/orlow molecular weight polyols and optionally other compounds containinggroups which are reactive with isocyanates for the production ofpolyurethanes. Examples of their use in the production of polyurethanelacquers, foils, coatings, elastomers and sealing compounds or fillers,but they are preferably used for the production of polyurethane foams.In order to ensure sufficient flame resistance, the polyamines accordingto the invention are used in such amounts that the finished polyurethanecontains at least 0.5% by weight and preferably 1 to 5% by weight ofphosphorus.

Another object of this invention is therefore to provide a process forthe preparation of polyurethane from polyisocyanates, high molecularweight and/or low molecular weight polyols and other compoundscontaining groups which are reactive with isocyanates, characterized inthat the compounds which are reactive with isocyanates include those ofthe general formula: ##STR7## wherein A, B and X have the meaningindicated above, and which are used in such an amount that thepolyurethane contains at least 0.5% by weight of phosphorus.

The isocyanates which may be used as starting components according tothe invention include aliphatic, cycloaliphatic, araliphatic, aromaticand heterocyclic polyisocyanates as described in, for example, W.Siefken in Justus Liebigs Annalen der Chemie, 562, pages 75 to 136.Examples include ethylene diisocyanates;tetramethylene-1,4-diisocyanates; hexamethylene-1,6-diisocyanate;dodecane-1,12-diisocyanate; cyclobutane-1,3-diisocyanate;cyclohexane-1,3- and -1,4-diisocyanate and mixtures of these isomers,1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl cyclohexane, (see e.g.,U.S. Pat. No. 3,401,190); hexahydrotolylene-2,4- and -2,6-diisocyanateand mixtures of these isomers; hexahydrophenylene-1,3- and/or1,4-diisocyanate; perhydrodiphenylmethane-2,4'- and/or4,4'-diisocyanate; phenylene-1,3- and -1,4-diisocyanate; tolylene-2,4-and -2,6-diisocyanate and mixtures of these isomers,diphenylmethane-2,4'- and/or 4,4'-diisocyanate;naphthylene-1,5-diisocyanate; triphenylmethane-4,4',4"-triisocyanate;polyphenylpolymethylenepolyisoxyanates which can be obtained by anilineformaldehyde condensation followed by phosgenation and which have beendescribed in British patent Specification Nos. 874,430 and 848,671, mand p-isocyanatophenylsulphonylisocyanates as described in U.S. Pat. No.2,454,606; perchlorinated arylpolyisocyanates as described in U.S. Pat.No. 3,277,138, polyisocyanates which contain carbodiimide groups asdescribed in U.S. Pat. No. 3,152,162, the diisocyanates described in U.SPat. No. 3,493,330, polyisocyanates which contain allophanate groups asdescribed in British patent Specification No. 994,890, Belgian Pat. No.761,626 and published Dutch patent application No. 7,102,524;polyisocyanates which contain isocyanurate groups as described in U.S.Pat. No. 3,001,973, German Pat. Nos. 1,022,789; 1,222,067 and 1,027,394;and German Offenlegungsschriften Nos. 1,929,034 and 2,004,048;polyisocyanates which contain urethane groups as described in BelgianPat. No. 752,261 or U.S. Pat. No. 3,394,164; polyisocyanates whichcontain acylated urea groups as described in German Pat. No. 1,230,778;polyisocyanates which contain biuret groups as described in U.S. Pat.Nos. 3,124,605 and 3,201,372 and British patent Specification No.889,050; polyisocyanates prepared by teleomerization reactions asdescribed in U.S. Pat. No. 3,654,106; polyisocyanates which containester groups such as those mentioned in British patent SpecificationNos. 965,474 and 1,072,956, U.S. Pat. No. 3,567,763 and German Pat. No.1,231,688, and reaction products of the above mentioned isocyanates withacetals as described in German Pat. No. 1,072,385 as well aspolyisocyanates which contain polymeric fatty acid groups as describedin U.S. Pat. No. 3,455,883.

The distillation residues which are obtained from the production ofisocyanates and which still contain isocyanate groups may also be used,optionally dissolved in one or more of the polyisocyanates mentionedabove. Any mixtures of the above mentioned polyisocyanates may also beused.

It is generally preferred to use readily available polyisocyanates suchas tolylene-2,4- and 2,6-diisocyanates and mixtures of these isomers("TDI"); polyphenyl-polymethylenepolyisocyanates which can be obtainedby aniline formaldehyde condensation followed by phosgenation ("crudeMDI"), and polyisocyanates which contain carbodiimide groups, urethanegroups, allophanate groups, isocyanurate groups, urea groups or biuretgroups ("modified polyisocyanates").

The starting components to be used according to the invention alsoinclude compounds which contain at least two hydrogen atoms which arecapable of reacting with isocyanates and which generally have amolecular weight of 400 to 10,000. In addition to compounds whichcontain amino groups, thiol groups or carboxyl groups, the compounds ofthis kind are in particular polyhydroxyl compounds, especially compoundshaving a molecular weight of 600 to 8000, preferably 800 to 6000, whichcontain 2 to 8 hydroxyl groups. Examples of such compounds includepolyesters, polyethers, polythioethers, polyacetals, polycarbonates orpolyester amides having at least 2, generally 2 to 8 and preferably 2 to4 hydroxyl groups, of the kind which are generally known for themanufacture of both homogeneous and cellular polyurethanes.

Suitable polyesters having hydroxyl groups include the reaction productsof polyhydric alcohols (preferably dihydric alcohols with the optionaladdition of trihydric alcohols) and polybasic, preferably dibasiccarboxylic acids. Instead of free polycarboxylic acids, thecorresponding polycarboxylic acid anhydrides or correspondingpolycarboxylic acid esters of lower alcohols or mixtures thereof may beused for preparing the polyesters. The polycarboxylic acids may bealiphatic, cycloaliphatic, aromatic and/or heterocyclic and may besubstituted, for example with halogen atoms, and/or unsaturated. Thefollowing are mentioned as examples: succinic acid; adipic acid; subericacid; azelaic acid, sebacic acid; phthalic acid; isophthalic acid,trimellitic acid, phthalic acid anhydride; tetrahydrophthalic acidanhydride; hexahydrophthalic acid anhydride; tetrachlorophthalic acidanhydride; endomethylenetetrahydrophthalic acid anhydride; glutaricacid; maleic acid; maleic acid anhydride; fumaric acid; dimeric andtrimeric fatty acids such as oleic acid, if desired mixed with monomericfatty acids, dimethylterephthalate or terephthalic acid bis-glycolester. Suitable polyhydric alcohols include ethylene glycol;propylene-1,2- and -1,3-glycol, butylene-1,4- and -2,3-glycol,hexane-1,6-diol, octane-1,8-diol, neopentyl glycol, cyclohexanedimethanol (1,4-bis-hydroxymethylcyclohexane),2-methyl-1,3-propane-diol; glycerol; trimethylolpropane;hexane-1,2,6-triol; butane-1,2,4-triol; trimethylolethane;pentaerythritol; quinitol; mannitol and sorbitol; methyl glycoside;diethyleneglycol; triethyleneglycol; tetraethyleneglycol;polyethyleneglycols; dipropyleneglycol; polypropyleneglycols; dibutyleneglycol and polybutyleneglycol. The polyesters may contain a proportionof carboxyl groups in end positions. Polyesters of lactones such asε-caprolactone or hydroxycarboxylic acids such as ω-hydroxycaproic acidmay also be used.

The polyethers having at least 2, generally 2 to 8 and preferably 2 or 3hydroxyl groups which may be used according to the invention are alsoknown per se and are prepared, for example, by the polymerization ofepoxides such as ethylene oxide, propylene oxide, butylene oxide,tetrahydrofuran, styrene oxide or epichlorohydric. Each may be preparedon its own, e.g., in the presence of BF₃, or by chemical addition ofthese epoxides, if desired as mixtures or successively, to startingcomponents which contain reactive hydrogen atoms, such as water,alcohols or amines, e.g. ethylene glycol, propylene-1,3- or -1,2-glycol,trimethylol propane, 4,4'-dihydroxydiphenylpropane, aniline, ammonia,ethanolamine or ethylene diamine. Sucrose polyethers such as thosedescribed in for example, German Auslegeschriften Nos. 1,176,358 and1,064,938, may also be used according to the invention. It is frequentlypreferred to use those polyethers which contain predominant amounts ofprimary OH groups (up to 90% by weight, based on all the OH groupspresent in the polyether). Polyethers modified with vinyl polymers,e.g., those obtained by the polymerization of styrene and acrylonitrilein the presence of polyethers (U.S. Pat. Nos. 3,383,351; 3,304,273;3,523,093 and 3,110,695 and German Pat. No. 1,152,536) andpolybutadienes which contain OH groups are also suitable.

Suitable polythioethers include in particular the condensation productsobtained by the condensation of thiodiglycol either on its own and/orwith other glycols, dicarboxylic acids, formaldehyde, aminocarboxylicacids or amino alcohols. The products obtained are polythio mixedethers, polythio ether esters or polythioether ester amides, dependingon the cocomponents.

Suitable polyacetals include the compounds which can be prepared fromglycols such as diethylene glycol, triethylene glycol,4,4'-dioxethoxy-diphenyldimethylmethane, hexanediol and formaldehyde.Polyacetals suitable for the purpose of the invention may also beprepared by the polymerization of cyclic acetals.

Suitable polycarbonates having hydroxyl groups include those known perse, e.g. those which can be prepared by the reaction of diols such aspropane-1,3-diol, butane-1,4-diol and/or hexane-1,6-diol ordiethyleneglycol, triethyleneglycol or tetraethyleneglycol withdiarylcarbonates such as diphenylcarbonate or phosgene.

Suitable polyesteramides and polyamides include such compounds as thepredominantly linear condensates obtained from polyvalent saturated andunsaturated carboxylic acids or their anhydrides and polyvalentsaturated and unsaturated amino alcohols, diamines, polyamines and theirmixtures.

Polyhydroxyl compounds which already contain urethane or urea groups andmodified or unmodified natural polyols such as castor oil, carbohydratesor starch are also useful. Addition products of alkylene oxides withphenolformaldehyde resins or with urea formaldehyde resins may also beused according to the invention.

Examples of these compounds which may be used according to the inventionhave been described in High Polymers, Vol. XIV, "Polyurethanes,Chemistry and Technology" by Saunders-Frisch, Interscience Publishers,New York, London, Volume I, 1962, pages 32-42 and pages 44-54 and VolumeII, 1964, pages 5-6 and 198-199 and in Kunststoff-Handbuch, Volume VII,Vieweg-Hochtlen, Carl-Hanser-Verlag, Munich, 1966, e.g. on pages 45 to71.

Compounds having a molecular weight of 32 to 400 which contain at leasttwo hydrogen atoms capable of reacting with isocyanates may also be usedas starting compounds according to the invention. These are alsocompounds which contain hydroxyl groups and/or amino groups and/or thiolgroups and/or carboxyl groups, preferably hydroxyl groups and/or aminogroups, and they act as chain lengthening agents or cross-linkingagents. These compounds generally contain 2 to 8 hydrogen atoms capableof reacting with isocyanates, and preferably 2 to 3 reactive hydrogenatoms. The following are mentioned as examples of such compounds:ethylene glycol; propylene-1,2- and -1,3-glycol, butylene-1,4- and-2,3-glycol, pentane-1,5-diol, hexane-1,6-diol, octane-1,8-diol,neopentyl glycol, 1,4-hydroxymethylcyclohexane,2-methyl-1,3-propanediol, glycerol, trimethylolpropane,hexane-1,2,6-triol, trimethylolethane, pentaerythritol, quinitol,mannitol and sorbitol, diethyleneglycol, triethyleneglycol,tetraethyleneglycol, polyethyleneglycols having a molecular weight up to400, dipropyleneglycols, polypropylene glycols having a molecular weightup to 400, dibutylene glycol, polybutylene glycols having a molecularweight up to 400, 4,4'-dihydroxydiphenylpropane,dihydroxy-methylhydroquinone, ethanolamine, diethanolamine,triethanolamine, 3-aminopropanol, ethylenediamine, 1,3-diaminopropane,1-mercapto-3-aminopropane, 4-hydroxyphthalic acid or 4-amino-phthalicacid, succinic acid, adipic acid, hydrazine, N,N'-dimethylhydrazine and4,4'-diaminodiphenylmethane.

Water and/or readily volatile organic substances may be used accordingto the invention as blowing agents. Suitable organic blowing agentsinclude acetone, ethyl acetate, halogenated alkanes such as methylenechloride, chloroform, ethylidene chloride, vinylidene chloride,monofluorotrichloromethane, chlorodifluoromethane anddichlorodifluoromethane as well as butane, hexane, heptane anddiethylether. The effect of a blowing agent can also be obtained by theaddition of compounds which decompose at temperatures above roomtemperature to liberate gasses. Such compounds include nitrogen, e.g.azo compounds such as azoisobutyric acid nitrile. Other examples ofblowing agents and details concerning the use of blowing agents may befound in Kunststoff Handbuch, Volume VII, published by Vieweg andHochtlen, Carl-Hanser-Verlag, Munich 1966, e.g. on pages 108 and 109,453 to 455 and 507 to 510.

Catalysts are frequently used in the process according to the invention.Suitable catalysts include those known per se, e.g. tertiary amines suchas triethylamine, tributylamine, N-methylmorpholine, N-ethylmorpholine,N-cocomorpholine N,N,N',N'-tetramethyl-ethylenediamine,1,4-diazo-bicyclo-(2,2,2)-octane,N-methyl-N'-dimethyl-aminoethyl-piperazine, N,N-dimethylbenzylamine,bis-(N,N-diethylaminoethyl)-adipate, N,N-diethylbenzylamine,pentamethyldiethylenetriamine, N,N-dimethylcyclohexylamine,N,N,N',N'-tetramethyl-1,3-butanediamine,N,N-dimethyl-β-phenylethylamine, 1,2-dimethylimidazole and2-methylimidazole. Mannich bases known per se which have been obtainedfrom secondary amines such as dimethylamine and aldehydes, preferablyformaldehyde, or ketones such as acetone, methyl ethyl ketone orcyclohexanone and phenols, such as phenol, nonylphenol or bis-phenol mayalso be used as catalysts.

Catalysts in the form of tertiary amines which contain hydrogen atomscapable of reacting with isocyanate groups include e.g. triethanolamine,triisopropanolamine, N-methyldiethanolamine, N-ethyldiethanolamine andN,N-dimethyl-ethanolamine and their reaction products with alkyleneoxides such as propylene oxide and/or ethylene oxide.

Silaamines containing carbon-silicon bonds as described in U.S. Pat. No.3,620,984 may also be used as catalysts. These include2,2,4-trimethyl-2-silamorpholine or1,3-diethylaminomethyl-tetramethyl-disiloxane.

Bases which contain nitrogen such as tetraalkylammonium hydroxides,alkali metal hydroxides such as sodium hydroxide, alkali metalphenolates such as sodium phenolate and alkali metal alcoholates such assodium methylate may also be used as catalysts. Hexahydrotriazines arealso suitable catalysts.

Organic metal compounds may also be used as catalysts particularlyorganic tin compounds. The organic tin compounds used are preferably tin(II) salts of carboxylic acids, such as tin (II) acetate, tin (II)octoate, tin (II) ethyl hexoate and tin (II) laurate; and tin (IV)compounds such as dibutyl tin oxide, dibutyl tin dichloride, dibutyl tindiacetate, dibutyl tin dilaurate, dibutyl tin maleate and dioctyl tindiacetate. All the catalysts mentioned above may, of course, be used asmixtures.

Other examples of catalysts to be used according to the invention anddetails concerning the action of these catalysts may be found inKunststoff-Handbuch, Volume VII, published by Vieweg and Hochtlen,Carl-Hanser-Verlag, Munich 1966, e.g. on pages 96-102.

The catalysts are generally used in a quantity of between about 0.001and 10% by weight, based on the quantity of compounds having a molecularweight of 400 to 10,000 which contain at least two hydrogen atomscapable of reacting with isocyanates.

Surface active additives such as emulsifiers and foam stabilizers mayalso be used according to the invention. Suitable emulsifiers includethe sodium salts of ricinoleic sulphonates or salts of fatty acids withamines such as oleic acid diethylamine or stearic acid diethanolamine.Alkali metal or ammonium salts of sulphonic acids such asdodecylbenzenesulphonic acid or dinaphthylmethane disulphonic acid or offatty acids such as ricinoleic acid or of polymeric fatty acids may alsobe used as surface-active additives.

The foam stabilizers used are mainly polyethersiloxanes, especiallythose which are water-soluble. These compounds generally have apolydimethylsiloxane group attached to a copolymer of ethylene oxide andpropylene oxide. Foam stabilizers of this kind have been described in,for example, U.S. Pat. Nos. 2,834,748, 2,971,480 and 3,629,308.

Other substances which may also be added according to the inventioninclude reaction retarders such as compounds which are acidic inreaction, e.g. hydrochloric acid or organic acid halides, cellregulators of a kind known per se such as paraffins, fatty alcohols ordimethylpolysiloxanes, pigments or dyes, stabilizers against ageing andweathering, plasticizers, fungistatic and bacteriostatic substances andfillers such as barium sulphate, kieselguhr, carbon black or whiting.

Other examples of surface-active additives, foam stabilizers, cellregulators, reaction retarders, stabilizers, plasticizers, dyes, fillersand fungistatic and bacteriostatic substances which may be usedaccording to the invention and details concerning methods of using theseadditives and their action have been described in Kunststoff-Handbuch,Volume VII, published by Vieweg and Hochtlen, Carl-Hanser-Verlag, Munich1966, e.g. on pages 103 to 113.

According to the invention, the starting materials are reacted by theknown one-step process, prepolymer process or semiprepolymer process, inmany cases using mechanical devices such as those described in U.S Pat.No. 2,764,565. Details concerning processing apparatus which may also beused according to the invention may be found in Kunststoff-Handbuch,Volume VII, published by Vieweg and Hochtlen, Carl-Hanser-Verlag, Munich1966, e.g. on pages 121 to 205.

When foams are to be produced according to the invention, foaming isfrequently carried out in molds, i.e. the reaction mixture is introducedinto a mold which may be made of a metal, e.g. aluminum, or a syntheticresin, e.g. an epoxide resin, and the foamable reaction mixture foams upinside the mold to form the molded product. The process of foaminginside the mold may be carried out in such a manner that a cellularstructure is obtained on the surface of the molded product or it can becarried out to produce a molded product having a compact skin andcellular core. According to the invention, the quantity of foamablereaction mixture introduced into the mold may be just sufficient toenable the resulting foam to fill up the mold, or if desired a largequantity of foamable reaction mixture may be introduced, in which casethe process employed is known as overcharging. This method has alreadybeen disclosed in, for example, U.S. Pat. Nos. 1,178,490 and 3,182,104.

So-called external mold release agents known per se e.g. silicone oils,are frequently used for the process of foaming in the mole.Alternatively, so-called internal mold release agents such as thosedisclosed in, for example, German Offenlegungsschirften Nos. 2,121,670and 2,307,589 may be used, if desired as mixtures with external moldrelease agents.

Cold setting foams may also be produced according to the invention (seeBritish patent specification No. 1,162,517, and GermanOffenlegungsschrift No. 2,153,086).

Foams may, of course, also be produced by the process of block foamingor by the double conveyor belt process known per se.

The following examples serve to explain the present invention. The partsand percentages given represent parts by weight or percentages by weightunless otherwise indicated.

EXAMPLE 1 2,6-Diamino-4-carbomethoxy-benzene-phosphonic acid dimethylester

45 g of (0.134 mol) of 2,6-dinitro-4-carbomethoxybenzene-phosphonic aciddimethylester are dissolved in 550 ml of methanol and hydrogenated at35° C and 60 excess atmospheres after the addition of 10 g of Raneynickel. The catalyst is filtered off after 4 hours and the solvent isthen evaporated off and the residue is freed from any remaining solventin a high vacuum.

Yield: 32 g = 82% of the theoretical, m.p. : 150°-151° C.

The IR and NMR spectra confirm its identity.

EXAMPLE 2 2,6-Diamino-4-carbomethoxy-benzene-phosphonic acid diethylester

The following compounds are used in a manner analogous to Example 1:

80 g (0.221 mol) of 2,6-dinitro-4-carbomethoxy-benzene-phosphonic aciddiethylester, 1000 ml of ethanol and 15 g of Raney nickel.

Yield: 61 g = 91% of the theoretical, m.p.: 105°-107° C. The IR andnuclear resonance spectra confirm the chemical structure of the reactionproduct.

EXAMPLE 3 2,6-Diamino-4-carboisobutoxy-benzene-phosphonic acid diethylester

108 g (0.268) of 2,6-dinitro-4-carboisobutoxy-benzene-phosphonic aciddiethylester in 1000 ml of ethanol are reduced with 20 g of Raney nickelat 50° to 60° C and 70 excess atmospheres by the method described inExample 1. The hydrogenation time is 3 hours.

Yield: 86 g = 93% of the theoretical, m.p.: 48°-50° C.

The IR and nuclear resonance spectra confirm the identity of theproduct.

EXAMPLE 4 2,4-Diamino-benzene-phosphonic acid-dimethyl ester (1)

113.5 g (0.479 mol) of 2,4-dinitro-benzene-phosphonic acid dimethylester (1) dissolved in 1500 ml of methanol are hydrogenated at 35° C and60 excess atmospheres in the presence of 25 g of Raney nickel.

Yield after crystallization of the crude product from toluene: 61 g =59% of the theoretical, m.p.: 140°-141° C.

The IR and NMR spectra and analysis of elements confirm the identity ofthe reaction product.

Calculated: C, 44.4; H, 6.0; N, 12.95; P, 14.35. Found: C, 44.3; H, 6.0;N, 13.0; P, 14.3.

EXAMPLE 5

A mixture of the following components is reacted in a closed mold:

100 Parts by weight of a polypropylene glycol having an OH number of 28which has been started on trimethylolpropane and modified with ethyleneoxide to result in 60% of primary hydroxyl end groups,

3.1 parts by weight of N-methylmorpholine,

0.5 parts by weight of N,N-dimethyl-ethanolamine,

1.0 parts by weight of a silicone stabilizer according to the generalformula ##STR8## 5.0 parts by weight of2,6-diamino-4-carboisobutoxy-benzenephosphonic acid diethyl ester, and

465 parts by weight of the polyisocyanate described below:

20 Parts of 1,2-propylene glycol are added to a mixture of 225 parts ofa mixture of 80% by weight of 2,4-tolylenediisocyanate and 20% by weightof 2,6,-tolylenediisocyanate and 274 parts of 4,4'-diphenylmethanediisocyanate at 60° C and the resulting mixture is reacted inside ametal mold for 30 minutes. The temperature is raised to 130° C after theaddition of 1 part of β-phenyl ethyl-ethyleneamine. The trimerizationreaction which occurs at this temperature is stopped after 21/2 hours,when the NCO content of the reaction mixture is 26.5%, by the additionof 1 part of methyl p-tolulenesulphonate.

The polyisocyanate obtained after diultion with 624 parts of an 80/20mixture of 2,4- and 2,6-tolylene diisocyanate has an NCO content of38.4% by weight, a viscosity of 24 cP at 25° C and a refractive indexn_(D) ⁵⁰ = 1,5738.

A foam which has the following mechanical properties is obtained:

    ______________________________________                                        Gross density  (DIN 53 420)  36 kg/m.sup.3                                    Tensile test   (DIN 53 571)  100 KPa                                          Elongation at break                                                                          (DIN 53 571)  110%                                             Pressure test  (DIN 53 577)  4.5 KPa                                          Pressure deformation                                                          residue        (DIN 53 572)  7.9%                                             Combustion test according to ASTM-D 1692-68                                   Assessment: self extinguishing                                                Average burning path: 83 mm                                                   Average extinction time 44 seconds.                                           ______________________________________                                    

What is claimed is:
 1. Flame retarding agents represented by the generalformula ##STR9## wherein A and B, either both represent --OR groupswherein R represents an optionally branched C₁ -C₈ alkyl group, or onerepresents a --OR group as defined above and the other represents anoptionally branched C₁ -C₁₇ alkyl group, andX represents hydrogen,halogen, an optionally branched C₁ -C₈ alkyl group, a C₆ -C₁₂ aryl oraralkyl group, NH₂, CF₃, CN, COOR , ##STR10## wherein: R' representshydrogen or an optionally branched alkyl or cycloalkyl group having 1-10C atoms and R" represents an optionally branched alkyl or cycloalkylgroup having 1-10 C atoms.
 2. The polyamines of claim 1, wherein A and Brepresent an --OR group in which:R represents an optionally branched C₁-C₄ alkyl group, and X represents hydrogen, chlorine, CH₃, NH₂, orCOOR'wherein: R' represents an optionally branched C₁ -C₄ alkyl group.3. The compound of claim 2, of the formula: ##STR11##
 4. The compound ofclaim 2, of the formula: ##STR12##
 5. The compound of claim 2, of theformula: ##STR13##
 6. The compound of claim 2, of the formula: ##STR14##